Force/Recon is pretty elite as far as the Marines go, can't think of any others really. They are considered SFOD, but so are expeditionary units...
Rangers aren't really considered elite as most guys (Delta, Green Berets) go through Ranger training anyway. IIRC Seals can go through Ranger training also. Ranger's aren't the 1337 like Delta/GB, plus those guys have done what Rangers go through. Oh well.
There are several Green Berets. Before Ed got discharged tonight, there were:
4 seals, 1 Green Beret, 1 Swat on alpha
4 Swat, 1 seal, 1 force/recon on bravo
1 Delta, 1 force/recon, 2 swat, 2 seals on bravo (i want to say the new guy who replaced ed is a seal)
1 CIA, 2 force/recon, 1 Green Beret, 1 seal, 1 swat on delta
It gets sort of odd. The swat guy on delta used to be force/recon. Lots of the swat guys used to be in the military. Baz on delta was in the marines. So it kinda overlaps somewhat.